1 files changed, 4 insertions, 2 deletions
diff --git a/src/log.h b/src/log.h
index cfc4471..497bab4 100644
--- a/src/log.h
+++ b/src/log.h
@@ -38,9 +38,11 @@ typedef enum log_priority {
 
 typedef int (*log_open_cb) (void);
 typedef void (*log_close_cb) (void);
-typedef void (*log_fmt_cb) (log_priority prio, const char *fmt, ...);
+typedef void (*log_fmt_cb) (log_priority prio, const char *fmt, ...)
+                            __attribute__ ((format (printf, 2, 3)));
 typedef void (*log_fmtex_cb) (log_priority prio, const char *srcfile,
-                              size_t line, const char *fmt, ...);
+                              size_t line, const char *fmt, ...)
+                              __attribute__ ((format (printf, 4, 5)));
 
 
 extern log_open_cb log_open;